摘要
采用热压烧结工艺(温度1850℃;压力30MPa;烧结时间60min)制备了ZrB2-ZrO2陶瓷基复合材料,采用XRD、SEM分析了材料表面和断口的物相特征和微观结构,采用三点弯曲和单边切口试验测试了材料的弯曲强度和断裂韧性。研究表明:增强相ZrO2的加入能缩短ZrB2-ZrO2复合材料的热压烧结致密化时间,促进了烧结致密化,随着ZrB2-ZrO2陶瓷材料中ZrO2含量(体积分数)的增加,弯曲强度表现为逐渐的上升趋势,材料ZrB2-15%ZrO2的强度仅为667MPa,而材料ZrB2-30%ZrO2的强度则增大到803MPa。材料在断裂过程中所发生大量t-ZrO2到m-ZrO2转变的相变使得材料的韧性随ZrO2含量的增多而逐渐增加,起到了相变韧化的效果。
ZrB2-ZrO2 ceramic matrix composites were prepared by hot-pressing method under the condition of 1 850 ℃/30 MPa/60 min.XRD and SEM were used to analyze the phase variation and microstructure.Three-point bending and single-edge notched method was used to measure its bending strength and fracture toughness.The results showed that adding ZrO2 was significantly beneficial to the restriction of grain growth of ZrB2 during densification.With the increase in volume fraction of ZrO2,good integration of the boundaries could be found from SEM/TEM images between the two phases of ZrB2 and ZrO2.The bending strength reached 667 MPa and 803 MPa for ZrB2-15%ZrO2 and ZrB2-30%ZrO2,respectively.Lots of phase transformations were found from t-ZrO2 to m-ZrO2,which played a role in toughening the composites.
基金
高等学校博士学科点专项科研基金资助项目(200802170012)
关键词
陶瓷基复合材料
相变
微观结构
强度
ceramic matrix composites
phase transformation
microstructure
strength
